Gear lapping machine



March 7, 1939. J, Mv CHR|STMAN 2,149,909

GEAR LAPPING MACHINE Filed Sept. 23, 1935 Trk/ff Hf @E ff i l [Ullmlllllllll )ci 7/ b Z l 44 y Patented Mar. 7, 1939 UNITED STATES PATENT OFFIQE GEAR LAPPING MACHINE Application September 23, 1935, Serial No. 41,802

Claims.

This invention relates primarily to apparatus for improving radially toothed machine elements such as gears and the like, for instance by the lapping or grinding of gear teeth after the formation of the teeth by the usual milling or cutting operations, and is a continuation in part of my prior led application Serial No. 17,728, filed April 22, 1935.

My prior application discloses a lapping ma- 1o chine which, in the preferred embodiment thereof, employs a fixed lap and a reciprocating support for the gear to be lapped', circumferential pressure being applied between the lap and the gear during relative reciprocation thereof by the application of torque to the gear support. The cooperating teeth of the gear and lap are maintained in their proper relation during the process by means of a guide which is associated with the gear support and which is illustrated as a tongue and groove device. If the gear being lapped is provided with straight teeth, the cooperating tongue and groove members of the guide are similarly straight and are arranged in parallel relation to the path of reciprocation of the gear; if the gear being lapped is provided with helical teeth, the tongue and groove members of the guide are formed to afford a similarlead.

It has been found that this guide is subject to Wear and requires frequent replacement necessitating loss of time in the operation of the machine and involving considerable expense, very accurate machining of the cooperating members of the guide being necessary in order that the gear teeth may properly cooperate with the lap teeth during relative reciprocation. It is therefore proposed as an essential feature of the present invention to provide a guide of this character which may be readily adjusted to eliminate clearance between the cooperating members thereof and to avoid 40 play and backlash in the lapping machine resulting from wear of the guide.

More specifically, it is an object of the invention to provide a guide for the reciprocating support of a lapping machine which comprises male and female members having a cooperating tongue and groove relationship, and means whereby the ratio of the width of the tongues to the width of the cooperating grooves may be increased to eliminate clearance therebetween. In one embodiment of the invention the tongues are directly expanded to effect the desired result; in another form of the invention the width of adjacent and successive tongues and of the cooperating grooves is progressively increased in one circumferential direction, whereby on the occurrence of wear the members of the guide may be indexed for the purpose of eliminating clearance.

While the present invention is concerned primarily with gear lapping machines of the character described which necessitate the employment of a guide comprising relatively movable members which must be fitted together with extreme accuracy, it will be appreciated that the inventive concept is applicable to machine elements of a generally similar nature for use in other combinations. Thus the guide disclosed in this application may be considered as constituting a splined or a screw and nut connection between any two relatively reciprocable members, it being conceivably highly desirable, for instance, to eliminate clearance between the cooperating toothed members of a screw and nut device by expansion of the teeth of either member, this expansion being either effected directly by deformation ofthe teeth or by the indexing of a properly designed structure to alter the cooperative relationship of the teeth and the tooth receiving recesses.

Further objects and features of the invention will be apparent from the following description d taken in connection with the accompanying drawing, in which Figure l is a side elevation, partly in section, of a gear lapping machine illustrating the application of one form of the present invention thereto;

Figure 2 is an elevation of one member of the guide for the reciprocating gear support shown in Figure l;

Figure 3 is a section on the line 3 3 of Figure 2; and

Figure 4 is a sectional view of the cooperating members of a guide constructed in accordance with another embodiment of the invention.

In order to facilitate an understanding of the invention, reference is made to the two embodiments thereof shown in the accompanying drawing and detailed descriptive language is employed. It will nevertheless be understood that no limitation of the invention is thereby intended, and that various changes and alterations are contemplated such as would ordinarily occur to one skilled in the art to which the invention relates.

While the guide which forms the principal feature of the present invention is applicable to gear lapping machines of other types and, in some degree, to machines of distinctly different nature, the drawing illustrates a machine of the character disclosed in my prior application above identified in which means is provided for impart- Yeo ' manner. Y'

ing relative reciprocating movement to a gear and a lap and for applying torque thereto during such reciprocation. Thus the machine may comprise a frame including a base 30 and a head portion 3| overlying the base, the head portion being supported by a standard 32 rising from the base. A shaft 35, carrying at its lower end a gear 31 to be lapped, is clamped or otherwise secured in position in a bracket 40. The details of the bracket form'no part of the present invention, it being sucient to state that the arrangement is such as to facilitate the application to and the removal from the bracket of the shaft 35 and the associated gear y31. The bracket 4111s provided with an upwardly directed boss 4l whichmay be keyed or otherwise secured against rotation on a shaft 44. The shaft 44 may be connected by means of a conventional type of rotating coupling, indicated at 1l, to a shaft 45, whereby-the shaft 44 is permitted to rotate freely. The shaft is supported ina conventional bearing guide-55 and is operatively connected by means of a pitman 58 to an eccentric 59 formed on or secured to a shaft 6U,` the'latter being carried by the head portion 3l of the frame and havingsecured thereto at its outer end a 'pulley or other conventional driving mechanism, not shown.

It will be' appreciated that by means of the mechanism thus far described, rotation of the shaft willeffect reciprocation of the shafts 45 and 44, the bracket 40, the shaft 35, and the gear 31 to be lapped, gear 31 meshing during Vthe operation with a stationary lap 6B which may be supported rigidly on the base 30 of the frame in any desired With a machine of this character it is possible to effect `very rapid reciprocation of the. gear in the lap and it is important that the shafts 44 and 45 and the gear 31 be accurately guided so that the gear teeth may follow the teeth of the lap and so that the pressure between the cooperating teeth maybe accurately controlled. With this end in View, it is proposed that the means which serves to guide the shaft 44 and associated elements during reciprocation thereof may also' be employed for the purpose of applying pressure between the cooperating teeth of the gear vand lap. Guide means of this character'is shown in the drawing as associated with the upper end of the shaft 44;

and is Villustrated as formed toV effect Vrotation of the shaft 44 during reciprocation thereof for the lapping of a gear havingA helical teeth, it being understood that the construction may be suitably Ymodified toprevent rotation of the shaft M'duringY reciprocation if the machine is to be used for the lapping of a gear kwith straight teeth. r

Thus the guide means is illustrated as comprising one or more cooperating tongueY and groove Yelements,rsuch elements constituting in effect a cam device Vin the event the teeth of the gear and lap are notstraight. The Vshaft 44 is formed with an enlarged portion having generally axially drected teeth 10 thereon, these teeth cooperating With corresponding internalteethr14 on a sleeve 15 which surrounds the shaft, an inner sleeve, 12 of bearing metal having the teeth 14 formed thereon being preferably cast within the sleeve Y 15 for this purpose, Vthe'bearing metal being suitably locked in position against'displacement with respect to the sleeve 15. Since the invention is illustrated as applied to theV lapping of a helically toothedgear, the cooperating teeth 10 and V14 are constructed to afford Va corresponding lead, it being understood that in the event a` gear having straight teeth is being lapped, the teeth 10 and Yployed in machines of this character.

14 will be correspondingly straight and generally parallel to the axis of reciprocation of the shaft 44 and associated members. Y Y

The sleeve 15 is supported for rotation in the head portion 3l of the frame and is provided at its lower end with an annular flange 16 having a toothed periphery which is engaged by a rack 18,A the latter being supported for reciprocation in aV substantially horizontal plane.

Assuming that the sleeve 15 `is held against rotation by retention o-f the rack 1B against displacement, it will be appreciated that the shaft 44 will be rotated during vertical reciprocation thereof, by reason of the cooperation of the teeth cient to apply pressure between one side of theVV cooperating gear teeth on the lap 68 and gear 31, the pressure so applied preferably being sufficien-t to ensure reasonably rapid abrasive action between the cooperating teeth while insufficient to cause the extrusion from between these cooperating teeth of the abrasive material usually em- In my prior application an arrangement is disclosed whereby automatic control of they rack 18 and of the pressure applied between the teeth of the gear and lap is accurately effected, but it is obvious that the rack 18 may be reciprocated manually if desired.

Referring now more particularly to the form of the guide means illustrated in Figures 2 and 3 of the drawing, it will be observed that the sleeve 15 is shown as provided with a plurality of apertures I5 extending therethrough, each of these apertures being threaded for the reception of a threaded element l 6 which may be provided with a slot I1 orv polygonal opening in the outer end thereof for engagement by a screw driver or other tool. -The apertures 5are preferably arranged in a series of circumferentially extending rows,

the several rows being spaced axially of the sleeve.` Ifdesired the apertures in eachrow may be stag-V gered slightly with respect to those in adjacent rows and may be so arranged as to form aseries of columnsgthe apertures in a given column extending both axially and circumferentially so as to conform generally to the helices of the teeth 14 formed in the bearingV metal sleeve 12 associated'with the sleeve 15. The apertures may further be so arranged that such a column of apertures extends along and overlies each of the heli-" eliminateVV clearance produced by wear of the teeth 14, the elements I6 are threaded down into theV apertures i5 Vsoas to exert pressure at the base of each recess 20, whereby the entire bearing metal sleeve 12Y may be deformed and Ythe'relatively soft metalthereof causedto flow to some extent to completely or partially fill' the cooperco1 Y from manufacturing tolerances and in order'toY A ating grooves between adjacent teeth 10 on the shaft 44. The adjustment may be rapidly effected and extreme accuracy of t between the cooperating teeth 'l0 and 74 will result, with consequent improvement in the accuracy of mesh between the cooperating teeth of the gear 31 and lap 68. The same guide may therefore be employed effectively for a much longer period of time and expensive replacements avoided.

Figure 4 of the drawing illustrates a further embodiment of the guide means which is constructed so that accurate adjustment of the clearance in the cooperating tongue and groove relation thereof may be readily effected. In this construction the teeth l0 formed on the shaft M vary progressively in Width in one circumferential direction. Thus the smallest of the teeth 'lil' is indicated at A, and adjacent and successive teeth, proceeding in a clockwise direction, are of gradually increasing width, the larg-est of the teeth it being indicated at B. The median lines of the teeth 'I are uniformly spaced about the periphery of the shaft; the teeth M are so shaped and distributed as to i'it snugly into the spaces between the teeth i9. Proper initial cooperation of the teeth l0 and 14 is readily effected by casting the bearing sleeve 72 about a formed toothed element. It will be appreciated that the progressive increase in the thickness of the teeth 'iii' is exaggerated in Figure 4 to facilitate an understanding of the structure; ordinarily a very considerably greater number of teeth are emn ployed, and the progressive increase in the width of the teeth is correspondingly slight.

On the occurrence of wear, the toothed portion of the shaft 1M is withdrawn from the sleeve l5 and is indexed with respect thereto in a counterclockwise direction, whereby each groove intermediate adjacent teeth iil receives a tooth 74 of larger width than the tooth which it originally received, the extent of indexing being of course sufficient to ensure a fairly close iit between the cooperating teeth lil and 'M'. As the result of this indexing, one or more of the smaller teeth 'lil' will be ren-dered useless since they will engage in cooperating tooth spaces intermediate the teeth M of substantially larger width. However, a sufiicient number of cooperating teeth will ordinarily be provided to ensure adequate bearing surface to enable the members of the guide to be indexed a number of times before replacement is necessary.

It will be appreciated that the invention in its broadest aspect contemplates the provision in relatively movable guide members having a tongue and groove connection, of means for adjusting the ratio of the width of the tongues to the width of the cooperating grooves, regardless of how this adjustment is effected. In one embodiment of the invention the means for effecting adjustment functions to directly expand the tongues; in the other form of the invention, this means includes increments in the width of adjacent and successive teeth of progressively larger magnitude, whereby indexing of the two members will accomplish the desired result.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

l. In a gear lapping machine, the combination with a toothed lap member, of a support for said member, a support for a toothed gear member to be lapped, said supports carrying said members in intermeshing relation, means for reciprocating at least one of sai-d supports and the member carried thereby, guide means associated with a reciprocated support for constraining the latter to follow the generally axial direction of the teeth of the gear and lap members during such reciprocation, and means whereby play and lost motion developed in said guide means as the result of wear may be eliminated.

2. In a gear lapping machine, the combination with a toothed lap member, of a support for said member, a support for a toothed gear member to be lapped, said supports carrying said members in intermeshing relation, means for reciprocating at least one of said supports and the member carried thereby, and guide means associated with a reciprocated support for constraining the latter to follow the generally axial direction of the teeth of the gear and lap members during such reciprocation, said guide means including a tongue and groove device associated with the reciprocated support, said device being adjustable to take up play resulting from wear in said tongue and groove device.

3. In a gear lapping machine, the combination with a toothed lap member, of a support for said member, a support for a toothed gear member to be lapped, said supports carrying said members in intermeshing relation, means for reciprocating at least one of said supports and the member carrie-d thereby, and guide means associated with a reciprocated support for constraining the latter to follow the generally axial direction of the teeth of the gear and lap members .during such reciprocation, said guide means including a tongue and groove device associated with the reciprocated support, the tongues of said device being expansible for eliminating clearance due to Wear.

4. In a gear lapping machine, the combination with a toothed lap member, of a support for said member, a support for a toothed gear member to be lapped, said supports carrying said members in intermeshing relation, means for reciprocating at least one of said supports and the member carried thereby, guide means associated with a reciprocated support for constraining the latter to follow the generally axial direction of the teeth of the gear and lap members during such reciprocation, said guide means including a tongue and groove -device associated with the reciprocated support, and means whereby the ratio of the width of the tongues to the width of the cooperating grooves of the device may be increased to eliminate clearance therebetween.

5. In a gear lapping machine, the combination with a toothed lap member, of a support for said member, a support for a toothed gear member to be lapped, said supports carrying -said members in intermeshing relation, means for reciprocating at least one of said supports and the member carried thereby, guide means associated with a reciprocated support for constraining the latter to follow the generally axial direction of the teeth of the gear and lap members during such reciprocation, said guide means including a tongue and groove device associated with the reciprocated support, and means whereby the ratio of the width of the tongues to the Width of the cooperating grooves of the device may be increased to eliminate clearance therebetween, said last named means including elements associated with said device and adjustable to effect expansion of said tongues. l

6. In a gear lapping machine, the combination with a toothed lap member, of a support for said member, a support for a toothed gear member to be lapped, said supports carrying said members in intermeshing relation, means for reciprocating at least one of said supports and the member carried thereby, guide means associated with a reciprocated support for constraining the latter to follow the generally axial direction of the teeth of the gear and lap members during such reciprocation, said guide means including a tongue and groove device associated wi-th the reciprocated support, and means whereby the ratio of the width of the tongues to the width of the cooperating grooves of the device may be increased to eliminate clearance therebetween, said last named means including increments of progressively larger magnitude in the width of adjacent and successive teeth, whereby the tongues may be indexed with respect to said grooves to obtain an accurate t therebetween.

'7. Guide means for controlling the relative rotative positions of two relatively reciprocable members, comprising'a tongue and groove connection betweensaid members, and means whereby the ratio of the width of the tongues to the width of the cooperating grooves of said con- Y nection may be increased tok eliminate clearance l therebetween. f

8. Gui-de means for controlling the relative roKV Y nection between said members, and means whereby the ratio of the width of the tongues to the width of the cooperating grooves of said connection may be increased to eliminate clearance therebetween, said means including a device for effecting direct expansion of said tongues.

9. Guide means for controlling the relative rotative positions of two relatively reciprocable members, comprisinga'tongue and groove connection between said members, and means whereby the ratio of the width of the tongues to the width of the cooperatinggrooves of said connection may be increased to eliminate clearance therebetween, said means including increments of progressively larger magnitude in the width of adjacent and successive teeth, whereby the tongues may be indexed with respect to said grooves to obtain an accurate fit therebetween.

l0. Guide means for relatively reciprocating members comprising male and female elements, said female element including a sleeve having a toothed annulus of deformable metal secured therein, said male element being grooved for cooperation with said annulus, and means associlast named means including a plurality of separate plugs threaded into said sleeve and engaging said annulus. Y

12. An expansible nut for use in screw and nut gearing comprising a sleeve having a plurality of threaded apertures therein, a toothed annulus of relatively soft metal forming an inner lining for said sleeve, and threaded elements in said. apertures engaging said annulus, whereby the annulus may be deformed and the teeth enlarged.

13. Guide means for relatively reciprocating elem-ents comprising male and female members,V

said members being provided with cooperating, circularly arranged, ribs and grooves, and means whereby the ratio of the width of the ribs to thev wi-dth of the grooves may be increased to eliminate clearance, said means being accessible for adjustment of such ratio during cooperative engagement of said members.

14. Guide means for relatively reciprocating elements comprising male and female members, said members being provided with cooperating ribs and grooves, andmeans whereby the ratio Vof the width of the ribs to the width of the grooves may be increased to eliminate clearance, said means including devices Yfor eifecting deformation and direct expansion of said ribs.

15. VGuide means for relatively reciprocating elements comprising male and female members, said members being provided with cooperating ribs and grooves, and means whereby the ratio of the width of the ribsY to the width of the grooves may be increased to eliminate clearance, said means including increments in the widthrof adjacent and successive teeth of progressively larger magnitude, whereby said members may be relatively indexed to effect an accurate iit between said ribs and grooves.

JOHN M. CHRISTMAN. 

